Circuit breaker



Nov. 26, 1940. c. E. IVES 2,222,843

CIRCUIT BREAKER Filed Nov. 20, 1936 2 Sheets-Sheet 1 Nov. 26, 1940. c.[was CIRCUIT BREAKER Filed Nov. 20, 1936 2 Sheets-Sheet 2 0 2 M- Lv qPatented Nov. 26, 1940 UNITED STATES PATENT OFFICE 12 Claims.

My invention relates to circuit interrupting and closing mechanism. Itrelates more in particular to circuit breakers of the type employed inthe ignition systems of automobiles, although not limited to such use,wherein a pair of contact points is provided, one stationary and theother adapted to be moved with respect to the stationary contact for thepurpose of opening and closing a circuit.

So-called breaker points or contact points employed in automobileignition systems, and mechanism used to control, adjust and aline suchpoints have had rather an extensive development. The mechanism nowgenerally employed represents a great advance in design, but still thereare many objectionable features and characteristics of common types ofbreaker points and controlling apparatus known to those skilled in theart, but which objectionable features and characteristics have not beenovercome.

One of the principal disadvantages and objections to breaker points andassociated apparatus now commonly employed is that true face contactbetween the breaker points is not obtained,

contact usually occurring even in the majority of new installations atone single point, that is, only over a small portion of the total areaintended for contact. This condition is aggregated by wear andadjustment of the points because of the fact that in common practice themovable point is adjusted through an arc and the fixed point is adjustedin a straight line. True parallelism, therefore, is substantiallyimpossible after adjustments have been made, and moreover,

is very seldom obtained in new installations. At-

tempts have been made to produce contact point supporting structures byvirtue of which contact 4 points will be self-alining and a truesurface-tosurface contact will be obtained. Such attempts,

however, have not met with success and the structures suggested have notgone into general use. There are many objections to suggestions forself-alining supports made in the past. Among the principal objectionsare the following: In high speed operation the contact arm must functionas a unit, and the support for the movable contact point should notpermit appreciable relative movement between the point and the contactarm. Structures suggested in the past have not supported the movablecontact point adequately and so have permitted such extreme movement as.to be objectionable, particularly at relatively high speeds. Anotherobjection is that the structures suggested have been either impossibleof production on a commercial basis, or so expensive as to make theiruse substantially prohibitive, or of such a fragile nature as to resultin frequent breakages. Still another objection is that supportingmechanism suggested in the past has not been capable of application 5 todifferent styles of contact arms and so the use in more than one type ofa system has been ,impossible, even assuming that other objectionsoutlined hereinabove had been overcome.

Accordingly, the principal object of my present 10 invention is theprovision of an improved form of support for a movable contact memberwhich obviates the objections outlined hereinabove.

Another object is the provision of an improved self-alining contactpoint. 15

Still another object is the provision of means for securing a contactpoint to a movable contact arm whereby self-alinement may take place,but wherein during operation the point functions substantially as iffixed rigidly to the .contact 20 arm.

Other objects and features will be apparent from the following detaileddescription taken with the accompanying drawings wherein Fig. 1 is anelevational view showing a station- 26 ary or fixed contact member, anda movable contact member embodying the'features of my invention.

Fig. 2 is an elevational view of the contact arm looking at right anglesto Fig. 1, along the line 2-2 of Fig. 1.

Fig. 3 is 'a longitudinal sectional view taken on the line 3-3 of Fig. 2looking in the direction of the arrows.

Fig. 4 is an enlarged sectional view taken on 35 the line 4-4 of Fig. 3looking in the direction of the arrows, and showing features ofconstruction of the movable contact point.

,Fig, 5 is a still further enlarged longitudinal sectional view taken onthe line 5-5 of Fig. 4. 40

Fig. 6 illustrates a combination rivet and support member shown beforethe assembly thereof.

Fig. '7 is a contact point carrying member adapted to be seated on themember shown in Figs. 8 to 13, inclusive, are views similar to Fig.

5 but showing modifications.

Fig. 14 is a plan elevation, partly in section, showing a modifiedcontact arm construction, and 50 Fig, 15 is an enlarged sectional viewtaken through the movable contact point and support therefor.

For convenience I have shown my invention as applied to the circuitbreaker mechanism em- 66 ployed in the ignition system of an automobile,and will describe it in that connection, although obviously it may haveother applications.

In Fig. 1 I illustrate generally a breaker mechanism produced inaccordance with my invention as applied to the ignition system of aninternal combustion engine. A movable contact arm I0 is pivoted on avertical post II. The movable contact arm carries a breaker point, thedetails of which will be described hereinafter, adapted to cooperatewith a fixed point l2 (indicated without a support), a cam 13 beingprovided in the usual manner to make and break contact at the breakerpoints by oscillating the contact arm l8 about the post II. A leafspring ll secured to the contact arm has a free end engaging between apin l6 so as normally to cause the contact arm to move in acounter-clockwise direction about its pivot and maintain contact betweenthe points.

Considering now the structure of the contact arm itself, this comprisesa unitary frame portion comprising a back I! provided with flanges l8and I9 forming a part thereof, and terminating in ears 2| and 22 whichcarry a sleeve 23. This sleeve engages around the post H and ispreferably made of bronze or other bearing material so as to have abearing action when in contact with post II.

The outer end of the back ll of the contact arm is apertured to receivea member 24 (Fig.

6). This member 24 comprises a rivet portion 24a, 9. head portion 24band a generally semispherical projection 24c which forms a seat for amovable contact supporting member as will be described. This member,preferably produced from stainless steel and functioning as will bedescribed hereinafter, is secured :to the back I! by extending the rivetportion 24a through the aperture provided in the back and riveting thesame into position to produce a final assembly as indicated in Figs. 3,4 and 5.

The breaker point assembly generally indicated by the referencecharacter 25 comprises a breaker point 26 preferably formed of tungstenor other suitable breaker point material, and a supporting member 21 towhich the breaker or contact point issecured by means. which will bedescribed. The supporting member 21 is provided with a generallysemi-spherical opening 28 adapted to engage over the projection 240 inthe manner shown more clearly in Fig. 5. A leaf spring 29 secured to theback I! of the contact arm by means of a rubbing block 3| fastened inposition by a rivet 32 has an opening equipped with an annular flange 33engaging against the slanting sides-of the supporting member 21 so as tohold the contact point assembly 25 against the projection 240 as anadjustable seat. The rubbing block is shown in the form of an L having acam follower 84 for engaging the cam l3, but this rubbing block may haveother shapes and the cam follower may be provided in other ways. Theconstruction shown, however, forms a firm support for the spring 29 aswell as for the cam follower. It is to be noted that the rubbing blockextends across the full width of the back I! so as substantially tocontact the flanges l8 and IQ of the contact arm thereby making itnecessary to employ only a single rivet for the purpose of securing afirm assembly.

The breaker point assembly 25, as previously described comprises atungsten disc or pellet 26 and the supporting member 21. This supportingmember 21 is preferably made of cold rolled steel for requisitestrength, and to facilitate attachment of the tungsten pellet. It ispreferably first coated with a thin layer of copper or other corrosionresisting material having suitable conductive characteristics, and thenassembled by utilizing a thin disk 88 of copper or other suitable metalbetween the tungsten pellet and its supporting member to act as a bondbetween the two members. The members are held under pressure and heat isapplied for example by a passage of an electrical current so as to fusethe copper which thus bonds the two sections together. During thisbonding operation some of the copper flows through the opening 21a andalso along\the outside of the member 21, fiow being induced by capillaryaction and supplemented by pressure so as further to coat thesurface ofthe member 21 through which contact is made.

The rubbing block 3| or at least the extension 34 thereof is made ofinsulating material in accordance with the usual practice in the type ofinstallation illustrated. The leaf spring 29 is formed of corrosionresisting material. Preferably it is coated with copper or formed of asuitable copper alloy in order to resist corrosion and also promoteelectrical contact.

In forming the member 24, as previously described, a stainless steelalloy is advisable. In the form shown in Fig. 6 before the rivet portion24a has been distorted the part is preferably made on a screw machine.During manufacture I preferably make the part 240 which is of generallysemi-spherical shape, somewhat oversize. This portion is then placed ina die having e'xactly the proper size and shape and by striking themember 240 a sharp blow the semi-spherical portion 240 is brought toexactly the proper size, and whatever tool marks may be present on itssurface are removed in the forming process. It

is to be noted that the part of the portion 24c 40 proper size byplacing a steel ball therein and 5 striking the steel ball a sharp blowso as to produce an opening of exactly the right size and shape whereinthe inside surface is substantially free of tool marks. Although theproportions may be changed, I have found that for contact arms for usein automobile ignition systems, the portion 240 may be made as part of ainch sphere, and the opening 28 is exactly the size to receive a inchsphere.

It will be noted that the surface of the semispherical member 240 andthe opening 28 are so proportioned that there is substantially a wedgingaction so as to cause the contact point assembly to have a firm andintimate contact with the member 24 whereby to decrease to a minimum thecontact resistance between these two members. The spring 28 bears firmlyagainst the angled outer walls of the supporting member 21 so as topromote contact at this point and also hold-the parts in intimateassembly. The tension of the spring and the shape of the parts is soproportioned that there is a strong wedging action and swiveling of themember 25 is resisted with considerable force by the action of thespring and the intimate association of contacting surfaces;

but the resistance to wedging action is not sufficient to prevent theautomatic alinement necessary to keep the face of the tungsten pellet 26dead in line with the opposing face of the stationary contact l2.

The diameter of the tungsten pellet 26 is preferably about .175 of aninch. This relatively large diameter not only results in the provisionof more than adequate contacting surface between the movable andstationary points, but it also serves to a considerable extent to keepthe movable point in proper alinement.

It is obvious that the angle between the center line and a line runningfrom the outside edge of the contact point and the outside edge of theopening 28 is relatively large, and obviously the wider this angle isthe easier it is for the movement of the stationary contact point tocorrect for errors in alinemem even though the spring 29 tends to holdthe assembly 21 quite firmly.

In assembling the breaker points of my invention, the stationary pointI2 is first placed in position, and set at approximately what theinstaller believes to be a suitable position. The contact arm is nowplaced in position and with the rubbing block alined with the flat sideof the cam l3 and the breaker points in contact, the contact arm ispulled back against the action of spring i4 and allowed to snap intoposition. One or two such actions will definitely cause the points tocome into exact alinement. The in ternal combustion engine is thenturned slightly until the high side of the cam engages the rubbingblock, and the stationary point I2 is adjusted, using a suitable gauge,until the proper width gap is provided between the two breaker points.If further precaution seems advisable, the internal combustion enginecan then be turned over further until the flat side of the cam is inline with the rubbing block and the contact arm can again be snappedonce or twice to be sure that the points are in alinement. It may benoted that according to the design of my breaker arm, proper alinementpreferably is secured in the manner described, and it is not expectedthat an improperly alined contact point will line itself up duringoperation of the engine. In general, however, even though the points areout of alinement they will usually run in but I prefer to initiateoperation with the points in true alinement using the precautions ininstallation described hereinabove.

Looking now at the modifications shown in Figs. 8 to 11, it will be seenthat the same general principles employed in the main embodiment areutilized in such modifications. Fig. 8 shows a modification wherein themember 240 is formed without the fiat portion shown in the main figures.In other words, both portions of the seat are true sections of a sphere.This form is not quite so satisfactory as the form shown in the mainfigures, although it may be used to advantage.

In Fig. 9 the seat i240 is formed directly in the back H1 of the contactarm. The movable contact assembly 25, spring 29 and other portions ofthe device may in this form remain identical with the form shown in thepreferred embodiment. The lower edge of the seat I 24c is shown round.The lower portion of this seat, however, may be formed fiat, if desired,as those skilled in the art will readily see by comparing, for example,the embodiment shown in Fig. 8 and the embodiment shown in the mainfigures.

In the form shown in Fig. 10, the back 2i! is formed with an annularopening through which an extension 4! on the movable contact assemblyI25 extends. The curve of the engaging surface is in the form of an arcof a sphere so that swiveling or alinement at these contacting surfacesis permitted. The spring and other portions of the supporting member I25may remain substantially the same.

In the form shown in Fig. 11, the back 3H is formed with a concave seat2240, and a semispherical projection Ill is provided on the supportingmember 225. In this form the other portions of the structure remainsubstantially unchanged. It is to be noted that the structure of Fig. 11is substantially the reverse of the structure of Fig. 9.

In each of the embodiments a seat is provided on the breaker arm for asupporting member which carries a contact face, preferably in the formof a pellet of tungsten, a seat cooperating with the seat provided onthe contact arm, and a shoulder engaged by a spring also carried by thecontact arm. In each of the embodiments also the engaging portion of theseat on the contact arm and the seat on the supporting member aresubstantially semi-spherical, the expression semi in the termsemi-spherical being used to indicate a part of rather than half of.Throughout the specification and in the claims it is to be understoodthat the term semi-spherical is employed in this sense. In each of theembodiments also there is a very firm contact over a relatively largearea of the seat so as substantially to produce a wedging action, butthis wedging action is limited so as not to prevent universal swivelingof the contact supporting member within the limits of the design so asto permit automatic self-alinement of the movable contact point.

The manner in'which I secure the result described in the precedingparagraph and other portions of the specification may be made clear byconsidering somewhat further a commonprinciple of design employedthroughout. One common feature is that a seat is provided on the contactarm, either by forming the body of the arm into a seat, or attaching aseparate seat carrying member to the contact arm body. The seatcooperates with a complementary seating surface on the movable breakerpoint assembly. There is another point of contact, however, between thebreaker point assembly and the contact arm body, namely, at the pointwhere the spring 29 engages the annular shoulder provided on the movablebreaker point assembly. All of these surfaces, four in number, arecurved (except in so far as certain surfaces may be modified while stillutilizing the same principle as will be explained hereinafter) and thesefour curved surfaces all comprise sections of spheres generated about acommon center. We may consider the common center as a virtual butuniversal pivot around which the movable breaker point assembly canswivel. If we look at Figure 5 we will find that the member 240 has asurface which comprises part of a sphere. If now we draw two chordsacross these surfaces and draw perpendicular lines on each chord, theselines will intersect at the center of a sphere of which the surfaces onthe member 240 comprise a part. Obviously, the inner semi-sphericalsurface on the member 21 has the same curve as member 240, and thissurface is also generated about the same center. Now take the outerspherical surface on the member 21; if we draw a series of lines as wedid when considering the spherical surfaces on member 24c, we find thatlines perpendicular to chords intersect at the same point. The same istrue of the inner surface on the flange 33 of gllre spring which engagesthe shoulder on member -The manner in which the principle illustratedabove may be modified can be shown in part by reference to modificationsalready described. However, by first studying the modification of Figs.12 and 13 the principle may be made somewhat clearer. In both of thesefigures the seat is shown formed from the body of the movable contactarm without the imposition of a separate seat member as illustrated inthe main embodiment. In each case, however, I may employ a separate seatmember, and therefore no significance should be attached to theparticular manner in which the seat is formed.

Referring now to Fig. 12, a portion "is formed into a seat 3240 which isof generally conical shape. This seat is engaged by a true semisphericalshaped body I on the movable breaker point assembly, which in this casehas the identical shape as shown in Fig. 11. The engaging seat formed bythe spring 29 in this case can be part of a cone, that is, the sidewalls maybe straight, because the shoulder on the movable contactassembly which is engaged by the spring comprises a section of a spheregenerated about the same center as the sphere comprising mem-' her I.The two radius lines shown in this figure indicate at their point ofintersection the center about which the spheres are generated.

Fig. 13 is similar to Fig. 12 in the combination of spherical and conesurfaces except that the seat "4c formed on the member I! comprises partof a sphere, and a recess 24! formed in the movable contact assemblycomprises part of a cone. The other portions of the design are the sameas illustrated and described in connection with Fig. 12.

With this additional structure to consider it should be clear to thoseskilled in the art that while in principle the four contacting surfacescomprise parts of a sphere ineach case each of the spheres beinggenerated about a common center, certain of the surfaces may comprisesections of a cone. I have found that two of the four surfaces maycomprise sections of a cone. If only two of the four surfaces comprisesections of a sphere, however, the two spherical surfaces should not bemutually engaging. The three possibilities, therefore, are for all foursurfaces to be sections of a sphere generated about a common center, forthree of the surfaces to be sections of a sphere as shown in Figs. 8, 9,10, and 11, or for two of the four. surfaces only to be sections of asphere as shown in Figs. 12 and 13. Preferably also the conical surfaceshould be generally perpendicular to a radius line drawn from the centerof the sphere to the point of contact between the spherical surface andthe cone surface. This is not absolutely essential but certainadvantages are secured by this general relationship.

For the purpose of illustrating a still further application of myinvention, I show in Fig. 14 the application of my present invention toa common type of dual system used in certain models of the Fordautomobile and in a somewhat modified form'also in other connections. Inthis arrangement there is a single cam l3 with two movable contact armsl0, one arranged to make contact while the other is breaking contact. Inthis design the contact arm body is usually formed of an insulatingmaterial such as a suitably treated phenolic resin. The details of theoperation and structure do not concern me in the present invention. Itis suflicient to say as is common in the automobile practice that thereis a stationary contact member which is adjustable to control the widthof the gap..

I Due to the character of the installation some modifications arerequiredin that portion thereof which relates to my invention, and thesemodifications are best shown by reference to Fig. 15 in which themovable contact assembly and supporting seat are shown in an enlargedsection.

The body I1 is apertured to receive a rivet 46 which carries a seat atone end thereof. The spring 29 usually provided in this particular formof installation is apertured to pass the rivet l6 and is engaged betweenan enlarged shoulder on the rivet and the body l1 whereby to provide thenecessary electrical contact required in the system. The movable contactassembly has the same general structure as described in connection withthe preferred embodiment, an inner generally spherical surface engagingthe seat and an outer annular surface on an extending shoulder beingengaged by a special form of spring support 4'! which is formed aroundthe main body II. It is obvious that by this construction there is verylittle spring action possible in the spring member 41, only enoughspring action being necessary to assure firm contact at all timesbetween all of the engaging surfaces, and to permit the necessary takeup in case of slight wear after prolonged operation. This comparativelyinflexible assembly is made possible because of the relatively freesliding movement which in turn is derivable from the proper design ofthe mutually engaging surfaces as described more in detail hereinabove.

In each form of the device it is to be noted, that while even though Ihave not provided what is commonly termed a high speed contact arm,nevertheless the contact arm of my invention is capable of operation atat least as high speeds as single piece fixed contact arms have beencapable of operating in the past. Inertia of the parts does not permitunseating of the swiveling portion of the contact arm carrying thecontact point, as is the case with other supposedly selfalining contactpoints heretofore produced.

I have described my invention in considerable detail in order that thoseskilled in the art may understand and know how to practice the same. Ido not limit myself, however, to the specific form or forms of theinvention shown and the invention is limited only by the scope of theappended claims.

What I claim as new and desire to protect by Letters Patentof the UnitedStates is:

1. In a circuit breaker, a contact arm having a seat, a movable breakerpoint assembly including a seat portion, a contact portion and anarcuate annular shoulder portion, the seats on the contact arm andbreaker point assembly engaging each other, one being convex andgenerally semi-spherical and the other concave and generallysemi-spherical, and a spring carried by the contact arm and engagingsaid arcuate annular shoulder generally tangentially thereof withsuflicient force to cause relatively great contact pressure, whereby todecrease electrical contact resistance, but not sufilcient pressure toprevent swiveling of the movable breaker point assembly on said seatwhereby to permit alinement of the contact portion with respect to astationary contact member cooperating therewith.

2. A circuit breaker as defined in claim 1 wherein the seat on thecontact arm is semispherical and convex and comprises part of a memberwhich includes a rivet portion extending through an aperture in a frameportion of the contact arm.

3. A circuit breaker as defined in claim 1, wherein said movable breakerpoint assembly comprises a section of ferrous metal carrying said seat,an annular shoulder, and a tungsten pellet bonded to said ferrousportion.

4. A circuit breaker as defined in claim 1, wherein said movable breakerpoint assembly comprises a section of ferrous metal carrying said seat,an annular shoulder, and a tungsten pellet bonded to said ferrousportion, said ferrous portion having a thin coating of a nonferrousmetal with high electrical conductivity, a layer of a bonding metalbeing provided between the ferrous portion and said tungsten pellet.

5. A contact arm as defined in claim 1 wherein said spring is in theform of a leaf spring having one end secured to the contact arm and theopposite end provided with an opening with an annular flangetherearound, said flange engaging the said annular shoulder onthe'movable breaker point assembly.

6. A contact arm as'defined in claim 1 wherein said spring is in theform of a leaf spring having one end secured to the contact arm and theopposite end provided with an opening with an annular flangetherearound, said flange engaging the said annular shoulder on themovable breaker point assembly, at least one engaging surface on saidannular shoulder and said flange comprising a section of a sphere.

7. In a circuit breaker, a swiveled contact memberhaving a contactingsurface on one side thereof, a convex spherical surface surrounding saidcontacting surface and facing in the same direction as said contactingsurface but spaced therefrom, and a concave spherical surface on theopposite side thereof substantially concentric with and having a smallerradius than said conthereof, a convex spherical surface surrounding saidcontacting surface and facing in the same direction as said contactingsurface but spaced therefrom, and a concave conical surface on theopposite side thereof, the axis of which substantially coincideswith'the center of said spherical surface.

10. In a circuit breaker, a swiveled contact member consisting of asolid generated by revolving a plane about one side as an axis, saidplane being described, in addition to said side, by two unlikeconcentric arcs joined by a line, another line substantially Prpendicular to said axis, a third line joining said perpendicular lineand the greater of the arcs, and a fourth line joining said side and thelesser of said arcs, the common center of said concentric arcs lying onsaid axis.

11. In a circuit breaker, a swiveled contact member consisting of asolid generated by revolving a plane about one side as an axis, saidplane being described, in addition to said side, by five lines and anarc, one of which lines intersects and is substantially perpendicular tosaid axis, a second line intersecting said axis and substantiallyperpendicular thereto in spaced relation to said first line, a thirdline intersecting said first line at a point apart from the intersectionthereof and said axis and divergent therewith, a fourth linesubstantially perpendicular to said axis intersecting said third linebut not said axis, and a fifth line intersecting said second line,substantially parallel with said axis and extending in a direction tointersect said third line if extended, said are joining said fourth andfifth lines, said are having a center lying on said axis at a pointbeyond the intersection thereof with said second and first lines.

12. In a circuit breaker, a swiveled contact member having a contactingsurface on one side thereof, a convex annular spherical surfacesurrounding said contact member and facing in the same general directionas said contacting surface, a spherical surface on the oppositeside ofsaid contact member forming a seat, said last]:

